Breech mechanism for automatic firearms



Jan. 18, 1944. w. l.. swARTZ BREECH MECHANISM FOR AUTOMATIC FIREARMSFiled Jan. 17, 1940 Patented Jan. 18, 1944 2,359,661 y BREECH MECHANISMFoa AUTOMATIC i FIREARMS William L. Swartz,`Weathersfieltl, Conn.,assigner to ColtsPatent IFire Arms Manufacturing-Com- "pany, Hartford,Conn., a corporationy of Connecticut Application January 17, 1940,.SerialNm y314,272

The present invention is particularly applicable. to ,automatic firearmsof the type shown in Patent No.,1,1525,065 to John M. Browning and inPatent Nc. 1,852,057 to Frederick T. Moore and Christian Pfeiffer, butit is not so limited.

The principal object of thepresent invention l.is to yprovide improved.means for preventing mpVementof the `transversely movable breech block,.during that period in the Acycle of operation .of the gun when theblockis intendedto be in .its `lower position.

`In the accompanying drawing I have shown the embodiment of theinvention which I now deem preferable, but it will be understood thatthe `drawing .is Jintended for illustrative purposes onlyand' is not tobe construed as defining or limiting the scope of the invention, theclaims forming ,a part of this specification being relied upon for thatpurpose.

' Of theI drawing:

l1 isa fragmentary side view of a gun embodyillgy the invention, acertain portion being broken away to show vinterior parts.

Eig, v:1L-is a fragmentary vertical sectional view taken along the line2-.2 of Fig. 1 but omitting certain parts.

Iteferring to the drawing, .I represents the main casmg which .comprises`spaced side plates .connectecl near their front ends with a trunnionblock 2, `In the drawing only the right hand side plate Ia isshown. At.the top of the casing is afeed box .3 .and .at the Irear of the feedboxis .a trigger kli.V These .parts need not .be described in detail `asthe invention does not relate to the detalsof the feed mechanism or of.-the firing mechanism. At the front and rear of the feed box are coverplates 5 and 6 which connect the .side plates.

The barrel-1 is longitudinally movable in an openingin .the `trunnionblock and it is detachably connected with a barrel extension 8 which is1ongitudinally movable in the casing, being guided at the top and at thebottom .by inward pro- .ecting anges on the side plates. 'Ihe barrelextensioncomprises two spaced -legs 8e and 8b. The barrel-and Ybarrelextension move rearward upon recoil andarereturned in the forwarddirection by the recuperator .spring 9. This spring acts through therecuperator rod I Il which -is connected atits rear end with a dependinglug `8c on the barrel extension 8.

.A150 longitudinally movable within the casing is a lock frame .I I,this frame being shown in Fig. 1 'in-the rear-ward position, which itoccupies at least momentarily after the .ring of each shot.

2 Claims. (01."89-3) Depending from .the lock frame II is a yoke I2 towhich are connected two transversely spaced tension rods I3. Thedepending lug .8 of the barrel extension 8 carries a yoke I4 havinglaterally projectingarms Ma (one of which is shown in Fig. 1*).vSupported in part on the arms I fla are tubes l5 which receive thetension rods I3 and which .also receive reaction .springs llisurrounding `the tension rods. 'These springs abut at their rear endsagainst plugs I5ab in the rear ends of the tube, andabut at theirforward ends FAX against projections (not shown) on the rods I 3 nearthe forward ends thereof.

Upon recoil, the barrel., barrel .extension and lock ,framemove rearwardsimultaneously, and the lock frame is at least momentarily held in itsrearward position asjshown in Fig. 1. The barrel and barrel extensionimmediately move forward under the influence of the recuperator springil,y as already stated, and the tubes l5 move forward at the same time,thus compressing the springs "I6, and tensioning the rods I3. Uponsubsequent Yrelease of the lock frame, thesprings I6 ,in cooperationwith the rods I3, move the lock frame forward, this frame with itsassociated parts serving to push a cartridge into the chamber of the.barrel as `explained in detail in the aforesaid patents.

`A breechblock Il is provided whichmoves bodily withthe barrel-extension8 and which is also movable vertically with respect to the barrelextension, being positioned .between the legs Ba and BD and being guidedby ribs 8d and 8B. The vertical movement of the breech block Il iseffected by an actuating lever I8 which is carried by the lock frame IIand which ismoved about its pivotal connection I8a by means `of a camstructure indicated in its entirety by I9 and depending from the maincasing at the left side thereof. The aetuating leverA I 3 hastransversely projecting studs 18h which are adapted to enter a T-slot Ila in the breech block. lWhen out of engagement with the actuatinglever, the breech block I1 is retained andsupported by a-stop 2,0, shownin Fig. 1. The stop 20 has a fiat surface on its top upon which thebottom surface of the breech block rests when it is in lowered positionso that the breech block will be properly positioned whereby the studs I81J will accurately enter the T-slot I'Ia during functioning of the gunto avoid jamming.

When the lock frame moves forward from the Position shown in Fig. 1, acartridge is pushed into the chamber of the barrel, as already stated.At the same time, a stud at I8 on the left side oi the actuating leverI8 travels along the cam groove me until it reaches the position shownby dot-and-dash line in Fig. 1. In this position the studs I8b on theactuating lever are about to enter the T-slot I`|a in the breech block.Continued forward movement of the lock frame and of the actuating levercauses the stud 'IIBc to move downward along the cam groove |9b thusrotating the actuating lever in the counterclockwise direction andmoving the breech block upward to its breech-closing position where itserves as an abutment for the cartridge.

Upon recoil, the barrel and barrel extension and the lock frameinitially move rearward in unison and during such movement a stud at ldon the left side of the actuating *leverl Vengages the cam surface |90.This engagement of the stud I8d with the cam surface |90. moves thelever IB in the clockwise direction and the lever in so moving causesdownward movement of the breech block.` This clockwise movement of thelever I8 carries the stud I8c into the cam groove |96. Continuedrearward movement causes the stud |8 to move. past the spring-pressedswitch |9 until the parts finally reach the position shown byrfull linesin Fig. 1. It will be understood that just before the lock frame and theassociated parts reach the fullline position shown in Fig. 1, the barreland barrel extension and associated parts, start to move forward to theposition shown in Fig. 1, .this forward movement separating` the breechblock fromthe actuat-v ing lever I8.

Further and more detailed illustration and description of the operatingmechanism for the breech blockv are to be found inthe before-mentionedpatents, and the foregoing brief description is sucient for purposes ofdisclosing the present invention.

It is highly desirable that the breech block be readily removable fromthe gun for inspection, cleaning or replacement. In order to permit suchready removal, the stop 20 is relatively movable in the direction shownin dot-and-dash lines in Fig. 1, and it ispivotally connected at 2|]ELwith the yoke i4. The stop is normally held in its upper operativeposition by a manually releasable means such as a spring-pressed detent2|. When the detentZl is withdrawn, the stop 20 can move to its lowerinoperative position as shown by dot-and-dash lines in Fig. 1. This re yleases the breech block I1 and permits it to dropl downward entirely outof the gun.

The breech block l1 can be put in place readily without interference bythe stop 2|),` and after it is in place the stop can be restored to theposition shown by full lines in Fig. '1, the stop thus again retainingthe block.

The movable stop 20 yand the detent 2| do not of themselves constituteany part'of the present invention, these being shown and claimed in theco-pending `application of George Webb for Breech mechanism forautomatic firearm, Serial No. 314,271, filed on even date herewith.

It will be observed that with thev breech block in the position shown inFig. 1 the yslot |'|n is properly positioned to receive the studs I8 onthe actuating lever I3 as xthe said lever moves forward. During lfiring,the gun is subject to some vibration which might take the breech blockout of the position shown in Fig. 1. During operation, the gun is notalways in the horizontal position as lshown, but it may be in an'inclined position or may even be in an inverted position. Under allpossible conditions of use it is essen-f tial that the breech block bein the position shown in Fig. 1 at the moment when the forward move mentof the lock frame is about to effect the en trance of the studs ith intothe slot Ha. To pre vent movement of the breech block out of th positionshown, a suitable means is provided suc] as the spring-pressed detent`21| shown clearly il Fig. 2, As shown, -this is', mounted in an apertun2da in the left leg 8b of the barrel extension, am is adapted to engagean upper edge portion o the block The detent 24 is provided with 1shoulder Zeb adapted to abut a seat 24c in thl aperture 2te tooperatively position the deten so that the inner end thereof may be inposltiol toiengage, but preferably and normally exert nl vappreciablepressure on, the upper edge of on side of the breech block. The detent24 is pressez into its operative position by means of a sprinl 25 whichabuts against a plug 26 threaded int: the aperture in the barrelextension leg. Thil detent serves to resist movement of the breecl blocki 'i upward out of its lower position vandthu: prevents any movementresulting from vibratior or resulting from the action of gravity.However, the detent 24 is cammed out of the Wa: when the breech block ispositively moved upward by the actuating lever I8.

It will be observed that the detent 2 4, engage: the block il in such away that it resists upwarc movement thereof, without however interferingwith free downward movement of the block wher the stop t!) is moved outof the way to release the block.

It should be quite apparent from the. foregoing and reference to thedrawing that thepdetent 24 is so located as not only to prevent upwardaccidental movement of the breech block by gravitationor as lthe resultof vibration; but.'V also kprovides for ready removal of the breechblocl-{foi inspection or replacement. This is due' to, Vthe fact thatthe detent 'M projects from the leg Ilt of the barrel extension inposition toerigage the top edge of the breech block. Hence, when Ythestop 20 is moved on its pivot 202' tothe dot-anddash line position ofFig. 1, the breech block may freely slide or drop out because there isnopositive locking engagement of the detent with .the breech block as inprior constructions of which I amI aware and wherein the detents enterkthe breech blocks adjacent their lower ends.v Under my invention, thedetent. 24 engages with or projects across the top edge ofthe breechblock when thebottom of the breech block is resting 'flatly on the stop2|) to locate and maintain the T-slot il in accurate alignment toreceive the studs I8lu as they approach the breechblock to engagein theT-slot |'|a to effect raising and loweringvof the breech block inaccordance with the functioning of the gun. y l

Inl actual practice I have found that my construction and arrangement ofmeans for supporting and stabilizing the breech block far surpasses' anymeans heretofore provided, of which Iavm` aware. This is due to the factthat the detent extends laterally through one of the legs ofthel barrelextension and is so located relative tothe accidental upward movement`due either tol vibration or gravitation resulting from vthe position ofthe mount.l Said means holds the breech block in said position in amanner greatly superior to any that has heretofore been possible byprior means since the latter resulted in disturbing the-location ofT-slot |18 with respect to the studs I8b for free and unobstructedentrance of the studs into said channel.

In the foregoing specification and the following claims, a number ofdescriptive terms have been used such as upwardj downward, vertical,top, and the like. A11 of said terms are used in a relative sense withrelation to the position of the rearm shown in the drawing when the sameare held in a vertical position. Said terms are to be considered in thesame relative sense regardless of the position in which the gun may bedisposed.

What I claim is:

1. In an automatic rearm, the combination of a casing, a longitudinallyreciprocable barrel,

a barrel extension connected with the barrel and positioned within thecasing, a breech block guided on the barrel extension for downward andupward movement out of and into breeech closing position, mechanismadapted to engage the breech block for moving the same downward andupward in timed relation with the reciprocation of the barrel and barrelextension, a stop carried by the barrel extension and having a faceadapted to engage the lower end of the breech block for limitingdownward movement thereof and properly positioning the same forengagement by said mechanism, the said stop being movable out of itsnormal position so as to permit free downward movement of the breechblock from the barrel extension, and a spring-pressed detent extendingtransversely through the barrel extension in a direction substantiallynormal to the longitudinal axis of the barrel and positioned to engageone side of the top of the breech block when its lower end is inengagement with said stop so as to resist upward movement of the breechblock away from said stop and permit free downward movement of thebreech block when said stop is moved out of its normal position, saiddetent also permitting the breech block to properly seat itself againstsaid face of said stop when the stop is in its normal position.

2. In an automatic fire arm, the combination of a casing, alongitudinally reciprocable barrel, a barrel extension connected withthe barrel and positioned within the casing, a breech block guided onthe barrel extension for downward and upward movement out of and intobreech closing position, mechanism adapted to engage the breech blockfor moving the same downward and upward in timed relation with thereciprocation of the barrel and barrel extension, a stop carried by thebarrel extension and having a face adapted to engage the lower end ofthe breech block for limiting downward movement thereof and properlypositioning the same for engagement by said mechanism, the said stopbeing movable out of its normal position so as to permit free downwardmovement of the breech block from the barrel extension, a springpresseddetent extending transversely through the barrel extension in adirection substantially normal to the longitudinai axis of the barreland positioned to engage one side of the top of the breech block whenits lower end is in engagement with said stop so as to resist upwardmovement of the breech block away from said stop and permit freedownward movement of the breech block when said stop is moved out of itsnormal position, said detent also permitting the breech block toproperly seat itseli against said face of said stop when the stop is inits normal position, and cooperative means disposed on said detent andbarrel extension for limiting the movement of the detent in breech blockengaging direction.

WILLIAM L. svi/ARTZ.

